Simultaneous electromechanical and capacitance characterization of top-gated LaAlO$_3$/SrTiO$_3$ heterostructures

ORAL

Abstract

LaAlO$_3$/SrTiO$_3$ (LAO/STO) heterostructures exhibit a sharp, hysteretic metal-insulator transition (MIT) with enhanced capacitance beyond the geometric limit when the interface is tuned by a biased top gate. To understand the physical origin of these behaviors, we investigate the electromechanical response and capacitance spectroscopy of top-gated LAO/STO heterostructures. Piezoelectric Force Microscopy (PFM) measurements demonstrate local variations in the hysteretic response, and capacitance measurements show carrier density changes at the LAO/STO interface as the top gate bias is varied. A strong correlation between PFM signals and capacitance signals is established by doing simultaneous measurements. The enhanced capacitance at the MIT is correlated with charging/discharging dynamics of nanoscale conducting islands at the interface, which can be imaged by spatially-resolved PFM.

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Authors

  • Feng Bi

    University of Pittsburgh

  • Mengchen Huang

    University of Pittsburgh, Department of Physics and Astronomy, University of Pittsburgh

  • Chung Wung Bark

    University of Wisconsin-Madison

  • Sangwoo Ryu

    Dept. of Materials Science and Engineering, University of Wisconsin-Madison, Wisconsin 53706, USA, University of Wisconsin-Madison

  • Chang-Beom Eom

    Dept. of Materials Science and Engineering, University of Wisconsin-Madison, Wisconsin 53706, USA, University of Wisconsin-Madison, Department of Materials Sciences and Engineering, University of Wisconsin-Madison

  • Jeremy Levy

    University of Pittsburgh, Department of Physics and Astronomy, University of Pittsburgh